This invention relates to densitometers and particularly to a reflection densitometer.
The measurement of reflection density is described, for example, in SPSE Handbook of Photographic Science and Engineering edited by W. Thomas, Jr. (John Wiley, 1972) at pages 839-40, and an optical system therefor is described at pages 857-858. A desirable feature of such densitometers is that it be highly compact, and for some purposes it should be a hand-held, self-contained instrument. With such restrictions, it is extremely desirable that the length of the optical system be very short; for example, desirably about 1" or less. When such a compact optical system is available, the lamp can be small and with a low energization requirement.